JPH09125280A - Electrolyzing method for removing copper from chloride bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method eliminating a defect such as deterioration of a cathode current efficiency, rising of an electrolyzing voltage and rising of a temp. in an electrolytic cell and capable of stably removing a surplus copper as a copper powder at a low cost. SOLUTION: In an electrolytic extracting method of the copper using a chloride soln. obtained by suspending a nickel mat containing the copper in a soln. containing the copper and the nickel and blowing chlorine to leach a valuable metal such as nickel and copper as an electrolyte, a nickel concn. of the electrolyte supplied to the electrolytic cell is kept in 100-180g/l and a copper concn. is kept in 30-40g/l, and pH is kept in 0-2.0. A remarkable, effect such as preventing the rising of the electrolyzing voltage due to a clogging of a diaphragm of an anode box, the rising of a liq. temp. incidental to this clogging, the clogging of a piping, etc., and capable of maintaining a copper removal electrolyzing operation with a high current efficiency is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decopperization process from a chloride bath, which is capable of leaching nickel matte with chlorine and producing high-purity electric nickel from the resulting leachate with high current efficiency. Is.

[0002]

2. Description of the Related Art Conventionally, as a method for obtaining electric nickel from a nickel mat, a nickel mat is suspended in a solution containing copper and nickel, and chlorine is blown into the nickel mat to leach out valuable metals in the nickel mat. There is a method of electrolytically extracting nickel from the leachate. in this way,
Because of the copper concentration in the leachate, some form of copper must be removed out of the system. As one of the methods,
There is a copper removal electrolytic method. This decopperization electrolysis method is, for example, placing an anode obtained by coating the surface of a titanium plate or mesh with a noble metal oxide in a box, using a titanium plate or a stainless plate as the cathode, and using copper on the cathode surface. Is a method of precipitating as copper powder.

[0003]

However, in this decoppering electrolysis operation method, the electrolytic solution to be supplied to the decoppering electrolysis step has a nickel concentration in the electrolytic solution and copper Since the concentration, pH, etc. are left to the discretion, good operating conditions are not always maintained. That is, the copper concentration in the electrolytic solution is 40
When it is more than g / liter, the amount of Cu ²⁺ increases in the decoppering electrolytic system, and this causes a disproportionation reaction with the copper powder generated on the cathode side Cu ⁰ + Cu ²⁺ = 2Cu ⁺ to redissolve the copper powder. As a result, there is a problem that the cathode current efficiency is reduced.

Further, when the nickel concentration or the copper concentration in the supplied electrolytic solution becomes high, the viscosity of the electrolytic solution becomes high and the diaphragm filter cloth used for the anode is clogged, and these increase the electrolysis voltage. This increase in electrolysis voltage raises the problem that the temperature of the electrolytic solution is set to 80 ° C. or higher and the anode box made of vinyl chloride is deformed, the filter cloth life is shortened, and the coating material on the anode surface is peeled off.

The present invention provides a method for eliminating excess copper as copper powder at low cost in a stable manner by eliminating the drawbacks of lowering the cathode current efficiency, raising the electrolysis voltage, and raising the temperature inside the electrolytic cell. It is intended to be provided.

[0006]

Means for Solving the Problems As a result of repeated studies for solving the above problems and achieving the above objects, the present inventors have found that the nickel concentration, copper concentration, pH, etc. in the electrolytic solution fall within specific ranges. The inventors have found that the objective can be achieved by the above, and have completed the present invention. That is, the present invention is a chloride solution obtained by suspending a nickel matte containing copper in a solution containing copper and nickel and leaching valuable metals such as nickel and copper by blowing chlorine to obtain an electrolyte solution. In the method for electrolytically extracting copper as described above, the nickel concentration of the electrolytic solution supplied to the electrolytic cell is 100 to 180 g / liter, the copper concentration is 30 to 40 g / liter, and the pH is 0 to 0.
The method is characterized by a decopperization electrolysis method from a chloride bath of 2.0, and a decopperization electrolysis method from a chloride solution using a nickel chloride solution, a hydrochloric acid solution and / or water for the preparation of the electrolytic solution. Is.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the method of the present invention, the nickel concentration of the electrolytic solution to be supplied to the electrolytic cell is limited to 100 to 180 g / liter, because nickel becomes nickel chloride when the nickel concentration is higher than this range. In addition, calcium in the electrolytic solution begins to precipitate as gypsum. The sulfate radical as a gypsum source is generated by oxidizing sulfur when the nickel matte is leached with chlorine. When salt or gypsum is deposited in this way, the piping is clogged or the diaphragm of the anode box is clogged. That is, if the piping is blocked, the operation must be stopped, and if the diaphragm of the anode box is clogged, the diaphragm resistance increases, the electrolysis voltage increases, and the same adverse effects due to the rise in the electrolyte temperature as in the conventional case occur. Occur. Further, if the nickel concentration is lower than this range, the water balance cannot be maintained in the next step, for example, the nickel electrowinning step, and the electrolyte must be discharged out of the system as waste liquid, which increases the manufacturing cost. Because.

When the copper concentration exceeds 40 g / liter,
The amount of divalent copper ions in the electrolytic cell increases too much, and the metallic copper generated at the cathode is redissolved by the disproportionation reaction, which lowers the current efficiency, while the copper concentration is less than 30 g / liter. Then, nickel starts to be electrodeposited on the cathode,
This is because the nickel content in the copper powder discharged outside the system increases and the nickel loss increases. For this reason, the copper concentration of the electrolytic solution supplied to the electrolytic cell must be within the above range.

Further, when the pH of the electrolytic solution is too high, the amount of nickel electrodeposited on the cathode increases and the efficiency of copper recovery decreases, resulting in an increase in nickel loss. As a result, iron in the electrolytic solution is deposited as hydroxide, the diaphragm of the anode box is blocked, and the electrolytic voltage rises. On the other hand, if the pH is too low, the metallic copper deposited at the cathode is chemically dissolved, resulting in a decrease in electrolysis efficiency. When the pH is less than 0,
The life of the diaphragm of the anode box and the coating of the anode surface is significantly reduced. Therefore, the pH is set to 0 to 2.0.

However, in order to obtain each of the above ranges, at least one kind of nickel chloride solution, hydrochloric acid solution and water is used for adjustment.

[0011]

Next, an embodiment of the present invention will be described.

Example 1: The composition of the decoppering electrolyte solution before each concentration adjustment was Ni 200 g / liter, Cu 60 g / liter (C
A solution of u ²⁺ /TCu=0.5 is added to nickel chloride (Ni
(60 g / liter, Cu <0.1 g / liter) solution was used as an electrolytic solution in which the copper concentration was adjusted as shown in the item of Example 1 in Table 1 below. The electrolysis was carried out at a current of 610 A / cathode sheet and a supply amount of 60 ml / A · H. From the obtained results, the cathode current efficiency was calculated using the following formula 1. Table 1 shows the results.

[0013]

[Formula 1] Cathode current efficiency (%) = (produced copper powder x copper grade (%) / (Cu 2 ⁺ electrochemical equivalent x energizing time x energizing current)

[0014]

[Table 1]

Comparative Example 1: Similar to Example 1, the copper concentration was adjusted as shown in the section of Comparative Example 1 in Table 1 to prepare an electrolytic solution, the same operation as in Example 1 was carried out, and the result was obtained. Is shown in Table 1. From the results shown in Table 1, the copper concentration is 30-40 g
It can be seen that good results were obtained in the range of / liter.

Example 2 The nickel concentration was kept constant at 180 g / liter, and the copper concentration (Cu ²⁺ /TCu=0.5) was adjusted as shown in the section of Example 2 in Table 2 below to prepare an electrolytic solution. The temperature of the electrolytic solution supplied to the electrolytic cell is 50 to 5
Table 2 shows the results obtained by the same operation as in Example 1 except that the temperature was 2 ° C.

[0017]

[Table 2]

Comparative Example 2: As in Example 2, the nickel concentration was kept constant at 180 g / liter, and the copper concentration (Cu ²⁺ / T).
Cu = 0.5) was adjusted as shown in the section of Comparative Example 2 in Table 2 to prepare an electrolytic solution, the electrolysis conditions were the same as in Example 2, and the obtained results are shown in Table 2. It can be seen from the results shown in Table 2 that good current efficiency can be obtained when the copper concentration is in the range of 30 to 40 g / liter, and the temperature in the bath does not rise so much.

Example 3: Copper concentration (Cu ²⁺ / TCu =
0.5) was kept constant at 35 g / liter, the nickel concentration was adjusted as shown in the section of Example 3 in Table 3 below to prepare an electrolytic solution, and the electrolytic conditions were the same as in Example 2 and the same as in Example 1. The results obtained are shown in Table 3.

Comparative Example 3: Copper concentration (Cu ²⁺ / TCu =
0.5) was kept constant at 35 g / liter, the nickel concentration was adjusted as shown in the section of Comparative Example 3 in Table 3 to prepare an electrolytic solution, the electrolytic conditions were the same as in Example 2, and the same operation as in Example 1 was performed. The obtained results are shown in Table 3.

[0021]

[Table 3]

From the results shown in Table 3, it can be seen that good current efficiency was obtained when the nickel concentration was within the range of the present invention. Further, in the case of 200 g / liter, the current efficiency of divalent copper ions was lowered, nickel deposition was observed, and the electrolytic cell voltage and the temperature inside the cell were also increased. Note that 80
Although the current efficiency is good even at g / liter, the water balance as a whole of nickel recovery is lost and the electrolytic solution has to be discharged out of the system, resulting in a high nickel production cost. It doesn't fit.

Example 4: Nickel concentration was 180 g / liter and copper concentration (Cu ²⁺ /TCu=0.5) was 35.
g / l, the pH was changed as shown in the section of Example 4 in Table 4 below, the electrolysis conditions were the same as in Example 2, and the same operation as in Example 1 was carried out to obtain the copper powder. I asked for the nickel grade inside. Table 4 shows the results.

Comparative Example 4: The same operation as in Example 4 was carried out except that the pH was changed to 2.2, and the obtained results are also shown in Table 4.

[0025]

[Table 4] From the results in Table 4, it can be seen that when the pH exceeds 2, the nickel grade in the copper powder sharply rises and the nickel loss increases.

[0026]

INDUSTRIAL APPLICABILITY According to the present invention, nickel concentration, copper concentration, pH
Since I tried to perform electrolysis operation with a specific range such as
It is possible to prevent voltage rise due to clogging of the diaphragm of the anode box, increase of liquid temperature accompanying this, prevention of clogging of pipes, etc., and it is possible to maintain the decoppering electrolytic operation with high current efficiency, which is a remarkable effect.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Susumu Makino 3-5-3 Nishihara-cho, Niihama-shi, Ehime Sumitomo Kinzoku Mines Besshi Works Nickel Factory

Claims (2)

[Claims] 1. A copper-containing nickel matte is suspended in a solution containing copper and nickel, and chlorine is blown into the solution to leach out a valuable metal to obtain a chloride solution. In the method, a nickel bath having a nickel concentration of 100 to 180 g / liter, a copper concentration of 30 to 40 g / liter, and a pH of 0 to 2.0 is used. Copper removal electrolytic method. 2. A nickel chloride solution for adjusting the electrolytic solution,
At least one kind of hydrochloric acid solution and water is used, and the decopperization electrolysis method from a chloride solution according to claim 1.